Manganous bromide (MnBr.sub.2) and cobaltous bromide (CoBr.sub.2) have wide use as catalysts and catalyst precursors. These compounds and manganese/cobalt/bromine mixtures are particularly useful as catalysts for the oxidative preparation of aromatic carboxylic acids.
While manganous bromide has been prepared by the direct reaction of manganese and bromine, the reaction is inefficient, particularly when conducted in solution. The inefficiency of the solution reaction results from two sequential side reactions, namely the reaction of manganese with water to liberate hydrogen and form Mn(OH).sub.2, followed by the oxidation of Mn(OH).sub.2 by Br.sub.2 to form Mn(OH).sub.3. This sequence of reactions often causes as much as 35% of the available manganese to be converted to Mn(OH).sub.3 rather than the desired product.
It would therefore be desirable to provide a process for the preparation of manganous bromide which is direct and efficient. It would be an additional benefit to provide a process which is capable of producing mixed manganese/cobalt/bromine systems from a single reaction mixture in a wide range of proportions.